1. Field of the Invention
The present invention relates to a portable electronic apparatus, known as an Integrated Circuit Card (IC Card), which incorporates an IC chip having, e.g., a nonvolatile memory and a control element such as a CPU and, more particularly, to a portable electronic apparatus in which an access control method for an area of the memory is improved.
2. Description of the Related Art
A so-called IC card which incorporates an IC chip having, e.g., a nonvolatile memory and a control element such as a CPU has been developed as a portable storage medium. An IC card of this type stores an identification number as key data in its internal memory. When an identification number is externally input, it is collated with the registered identification number stored in the memory, and subsequent memory access is enabled or disabled in accordance with the collation result.
A conventional IC card is disclosed in Japanese Patent Disclosure (Kokai) No. 60-160491, Tamada et al., Aug. 22, 1985. (U.S. patent application Ser. No. 699,099).
As a method of determining whether or not an access to an area is enabled, a plurality of identification numbers are stored in a memory, and identification data indicating an identification number to be collated when a corresponding area is to be accessed is stored in correspondence with areas. Thus, the collation result of the identification numbers is compared with the identification data for each access to determine whether or not an access is enabled.
However, if the identification data is commonly used for all the access instruction data, the access conditions for all the instruction data become the same, an access condition to an area cannot be finely set, and hence, an IC card system cannot be flexibly used.